Thursday, July 4, 2013

Difference between Mail-Contact and Mail-User

Many
of folks keep asking what the difference between Mail User and Mail Contact is.
So I thought to publish this here, so the folks can read it anytime for
reference.

Exchange
Server 2010 actually defines sixteen different types of recipients. With so many
recipient types, a certain level of confusion can be expected. One of the most
frequently misunderstood concepts is the difference between a mail contact and
a mail user.

Active
Directory contacts

Before we examine the concept of mail contacts versus mail users, let’s take a
moment to look at contacts in general. Contacts are Active Directory objects
that are totally independent of Exchange Server. If you look at Figure 1,
you’ll see that the Active Directory Users and Computers console
contains an option to create new contacts.

Existing
contacts are displayed in the console's Users container, alongside
regular user accounts. Contacts represent users who do not log into your
domain. For example, some Exchange organizations have contacts that represent
suppliers or customers.

An
Active Directory contact is really just a repository for information. For
example, a contact object can store an associated individual’s phone number,
mailing address, etc.

Exchange
2010 mail contacts

Mail contacts are an Exchange recipient type. They are essentially the same
thing as Active Directory contacts, but with one exception -- they are
mail-enabled.

Mail
contacts are created through the Exchange Management Console (EMC) by
right-clicking the Recipient Configuration container, then selecting the
New Mail Contact command. When you do, Exchange launches the New Mail
Contact wizard. The wizard gives you the option to create a new contact or
to mail-enable an existing Active Directory contact.

You
can create a new contact or mail-enable an existing contact in Exchange 2010.

You’ll
see that the wizard associates an alias and SMTP address with the existing
contact. You also have the option to create a new contact. This is because a
mail contact is the same thing as a mail-enabled contact.

Exchange
2010 mail users

Mail users are very similar to mail contacts. Both are Active Directory objects
that contain user contact information and an external email address. Likewise,
both mail users and mail contacts appear in the Global
Address List (GAL). However, there is one very important difference
between a mail contact and a mail user.

Mail
users are Active
Directory security principles. In other words, a mail user has an
Active Directory account they can use to log into your network. Therefore, a
mail user can access resources on your file servers, Printers and shared drive
etc. participate in Active Directory security groups and be managed the same
way as any other user.The only thing that differentiates a mail user from any
other user in an Exchange organization is that mail users cannot send and
receive Exchange mail. The user's account is a link to an external email
address.

I
also want to point out that some of the terminology used in Exchange circles
can be confusing. Microsoft refers to Active Directory users with Exchange
mailboxes as Mail Enabled Users; do not confuse this with mail users.
These mailboxes are also sometimes referred to as user mailboxes. I’ve
also seen corresponding accounts referred to as mailbox-enabled users.

Should
you use mail contacts or mail users in Exchange 2010?

So which is more beneficial -- mail contacts or mail users? The primary advantage
to using mail contacts is there are no licensing
requirements. A mail contact is just an Active Directory object.
There is no corresponding user account and no Exchange
Server mailbox. Therefore, there is nothing to license. In contrast,
mail users have an Active Directory account and require a client access license
(CAL).

While
the main benefit of using mail users is to access network resources within organization,
there is one other benefit worth mentioning. It is generally impossible to
convert a mail contact into a user mailbox. But if you want to turn a mail
contact into a mail-enabled user, you must delete the contact and create the
user account and mailbox. Also, mail users can be converted to mail-enabled
users with the Get-MailUser <user name> | Enable-Mailbox EMC
command.

Get-MailUser
–Identity “Gengaiyan” | Enable-Mailbox –Database “DB1”

Both
mail contacts and mail users have their place. That said, if you decide to use
mail users, it is important to properly license them. A Windows CAL is
required, but an Exchange Server license is not required because the user
doesn’t have an Exchange mailbox.